Optical sensing of watthour meter disc rotation has been known heretofore. For example, T. R. Polenz U.S. Pat. No. 3,602,703, dated Aug. 31, 1971, shows a photodetector for sensing six slots in the disc of a kilowatthour meter to provide pulses indicative of power usage. These pulses are used to control high-priority and low-priority loads. The control system estimates the total power requirements of the highest priority and other loads and allocates the available power thereto in a predetermined manner. Also, C. J. Snyder et al. U.S. Pat. No. 4,081,746, dated Mar. 28, 1978, shows a photo-electric pickup for sensing the passage of the anti-creep hole in the disc of a multiple-rate meter. The resultant pulses are used in the control system to cause the power usage to be totalized in a first register when the power usage is below a set point and to be totalized in a second register when the power usage is above the set point.
Electronic time-of-day metering systems have also been known. For example, W. R. Germer U.S. Pat. No. 4,050,020, dated Sept. 20, 1977, shows a KWH meter having three sets of dials including a standard KWH set, a first alternate (high-peak) rate set, and a second alternate (mid-peak) rate set that may be selectively clutched to the drive by the programmable control system depending on the time of day and the day of the week. The memory is pre-programmed for alternate meter operation. The system uses a 60 Hz power line time base clock and the clock time is compared to the stored time and a function control signal switches in an alternate set of meter dials. Also P. M. Johnston et al. U.S. Pat. No. 4,077,061, dated Feb. 28, 1978, shows a digital processing and calculating AC electric energy metering system that uses high-speed analog sampling of power voltage and current waves for accurate power measurement. These analog signals are converted to binary representation and processed in a programmed sequence controller and calculator to produce visual displays and output signals of hereinafter described electric energy parameters to be measured. Data pulses are transmitted through a remote metering telemetry system or for being recorded in a magnetic recorder type of receiver device. Input and output interfaces are used between the input signal sampling device and the processing system. A microprocessor is used for the calculations of certain parameters including kilowatt hours, Q-hour and volts squared as well as peak power usage or kilowatt demand and made available for direct input to the readout display. Manual switches are used to select the parameter to be displayed.
While these prior systems have been useful for their intended purposes, this invention relates to improvements thereover.